Reproduction and Sexual Maturity of European Sardine (Sardina pilchardus) in the Central Mediterranean Sea

Abstract

Understanding drivers of fish maturity is essential to predict the productivity, stability, and resiliency of exploited populations. Size at maturity for European sardine (Sardina pilchardus) in the Central Mediterranean Sea has never been published within rigorous peer review process. In the past, stock assessment working groups in the Mediterranean requested such information; however, the size at which 50% of the fish population reaches the sexual maturity (L50) often received weak estimates based on a single or few years of observation, which do not necessarily reflect the whole stock. To address this data gap for the Central Mediterranean Sea, the present research estimated size at maturity of European sardine in the Strait of Sicily. In the study period (2009–2017), sampled individuals exhibited significant differences in size range as well as in body condition and reproductive effort. Data also permitted a clear identification of the spawning season, starting in September–October and ending in March–April the following year. Along the analyzed period, the size at first maturity ranged from 108 to 124 mm (total length) for females and from 102 to 122 mm for males. Significant differences were recorded among genders and years. Moreover, a goodness-of-fit measure was proposed to assess the robustness and reliability of L50 estimates, and thus selecting those that minimize the fitting-associated errors. Finally, results suggested that the low proportion of immature individuals in the samples represents the main source of bias in L50 estimation and possible solution was also proposed.

Somatic Condition and Reproductive Potential as a Tandem in European Sardine: An Analysis with an Environmental Perspective in the Northern Adriatic (Gulf of Trieste)

“…Moreover, significant differences between the sexes in GSI were identified only for active spawners (Figure 3A), with larger values observed in females. Our results are similar to those of Basilone et al [12] for a study in the Central Mediterranean, although they differed from other studies in which males were identified as the individuals with the highest values of GSI [13]. According to Ganias et al [2], isometric ovarian growth has been shown for all the developmental stages in sardines except for hydration, and so the relative weight of the ovaries (i.e., the gonadosomatic index, GSI) remains stable with body size, except in this phase (i.e., corresponding to hydration and ovulation in females [48]).…”

“…The reproductive potential of the small pelagic European sardine (Sardina pilchardus (Walbaum, 1792)) depends on its spawning frequency and batch fecundity [8], as it is a multiple spawner species with an indeterminate annual fecundity that serially releases batches of pelagic eggs at intervals (i.e., batch spawner) within the spawning season [9,10]. Its spawning season occurs during the winter [2,11] along its distributional range, although monthly differences exist associated with sardine stock genetic features and environmental characteristics of the area [12]. Production of such a great number of eggs during an extended period requires a considerable amount of energy resources that can be obtained (1) from energy reserves accumulated prior to spawning, (2) directly from food input during the spawning season, or (3) from both sources [13] so that the population's reproductive potential can be influenced by the condition of the fish, which has a direct impact on their recruitment strength [8].…”

“…Moreover, the fish endocrine system is modulated by external and internal (size and/or age, storage levels, i.e., levels of sugars, amino acids, and lipids) conditions, and thus it can either complete reproductive development and spawning under an optimal environment or delay/abort reproduction under non-optimal circumstances [29]. Therefore, there exists high variability in terms of fish recruitment, biomass, and distribution, which are mostly dependent on environmental and climatic conditions [12]. In fact, it has been reported that higher catches and larger larval growth rates are found in areas with high chlorophyll concentrations [30], with water stratification and currents among the most important factors that modulate plankton productivity and availability and, therewith, better condition of the planktivorous fish [24].…”

Comparing otolith shape descriptors for population structure inferences in a small pelagic fish, the European sardineSardina pilchardus(Walbaum, 1792)

“…The size range among locations was restricted to the most similar to cover an identical age range and strict as possible to avoid multiple classes. Sample locations concerning Mediterranean waters had smaller sizes, related to the lower average adult individual size (Albo‐Puigserver et al ., 2021; Basilone et al ., 2021; Van Beveren et al ., 2016). Sample collection was opportunistic and primarily dependent on small pelagic trawls during research surveys.…”

Spatio-temporal connectivity and dispersal seasonal patterns in the Adriatic Sea using a retention clock approach

“…The peak of reproductive activity occurs between November and February, primarily depending on environmental parameters such as temperature (Zorica et al, 2019). In contrast to the AS, the spawning period for S. pilchardus appears to end earlier in other Mediterranean areas (Tsikliras et al, 2010;Basilone et al, 2021). The Adriatic anchovy spawns from the end of March (winter) to October (autumn), with its peak spawning season occurring in July (Zorica et al, 2020).…”